queue2: flush differently, avoiding deadlocks

Don't flush the file by closing and opening it but instead use g_freopen. This
avoids a deadlock in shutdown because we emit the temp-location property change
with the wrong lock held.

gst/playback/gstqueue2.c

@@ -1088,12 +1088,25 @@ gst_queue_close_temp_location_file (GstQueue * queue)
   queue->temp_file = NULL;
 }
 
+static void
+gst_queue_flush_temp_file (GstQueue * queue)
+{
+  if (queue->temp_file == NULL)
+    return;
+
+  GST_DEBUG_OBJECT (queue, "flushing temp file");
+
+  queue->temp_file = g_freopen (queue->temp_location, "wb+", queue->temp_file);
+
+  queue->writing_pos = 0;
+  queue->reading_pos = 0;
+}
+
 static void
 gst_queue_locked_flush (GstQueue * queue)
 {
   if (QUEUE_IS_USING_TEMP_FILE (queue)) {
-    gst_queue_close_temp_location_file (queue);
+    gst_queue_flush_temp_file (queue);
-    gst_queue_open_temp_location_file (queue);
   } else {
     while (!g_queue_is_empty (queue->queue)) {
       GstMiniObject *data = g_queue_pop_head (queue->queue);